This invention relates to a shock control device which is particularly suitable for use in construction of large buildings such as bridges, elevated highways or railways and the like.
In constructing bridges with long girders, it is general practice to support one end of the girder fixedly by a fixed shoe (bridge bearing) and the other end by a movable bearing to absorb elongation or contraction of the girder due to variations in the atmospheric temperature. The bearing at the junction of an upper and lower structure of such bridge, particularly the fixed bearing, is subjected to a great horizontal force at the time of earthquakes since the movable bearing shares the horizontal force only in a small amount comparable to a frictional force. The force imposed on the fixed bearing becomes extremely great with a lengthy or continuous girder.
In this connection, it is known to provide shock controlling devices in the lower work of a bridge in combination with the fixed bearings, the shock controlling devices being designed to show almost no resistance to a very slow motion of the girder or upper structure as experienced during its elongation or contraction due to temperature variations, showing a positive resistance only to an abrupt movement of the girder or upper work as caused by earthquakes to prevent concentration of impacts on the fixed bearings of the lower work.